feat(dex): solve constant product invariant with uneven weights

[NibiruHeisenberg]

Currently the constant product invariant only supports two assets (x and y) and works really well with equal weights, but not with unequal weights because the floating point exponentiation leads to loss of precision, which leads to significant slippage at large numbers.

For now, the constant product invariant only supports equal weights but for exploring how to support unequal weights would be a huge value add.

[NibiruHeisenberg]

10/31: lower priority

[matthiasmatt]

Also this will break the single asset join

[matthiasmatt]

Should we remove weights all together?